This invention relates to a vehicle safety light which provides a warning signal to approaching vehicles at night.
At night, vehicles parked on the street are subject to being side-swiped by passing vehicles, especially in inclement weather or when parked on a poorly lit side street. The risk to parked cars is especially prevalent at night, due to reduced visibility, from drivers who are inattentive or impaired. Accidents also occur on highways when an overtaking car misjudges the position of the side of the other car, as is more apt to happen at night, and swerves into it.
It is desirable then to have a means of indicating to the oncoming vehicles the position of the stationary vehicle. It has been suggested in the art, such as in U.S. Pat. No. 4,249,160 to Chilvers, to provide a vehicle light assembly responsive to oncoming incident light, such as headlights, which operates only at night when the vehicle is turned off. However, the methods suggested therein for detection of incident light and generation of responsive illumination have the drawback that they require comparison of the signal corresponding to the intensity of the incident luminance with a pre-determined threshold level which is difficult to set initially and maintain during use thereof. The efficiency and longevity of the power source are handicapped by the use of these comparison circuits because the devices that conventionally perform this operation, such as operational amplifiers, are considered to have high power consumptions. Therefore a need exists for a vehicle warning light which will operate at night in response to incident light and which is implemented by means of a simple, easily fabricated, low power consumption transistor circuit not dependent on threshold comparisons.